Aquatic Ecosystems 6.L.2.3 Summarize how the abiotic factors (such as temperature, water, sunlight, and soil quality) of biomes (freshwater, marine, forest,

Aquatic Ecosystems

6.L.2.3 Summarize how the abiotic factors (such as temperature, water, sunlight, and soil quality) of biomes (freshwater, marine, forest, grasslands, desert, Tundra) affect the ability of organisms to grow, survive and/or create their own food through photosynthesis.

Freshwater Ecosystems

• In aquatic environments, water temperature, the amount of sunlight present, and the amounts of dissolved oxygen and salt in the water are important.

33Aquatic EcosystemsAquatic Ecosystems

Rivers and Streams• Flowing freshwater environments vary from

small, gurgling brooks to large, slow-moving rivers.


• Naturally fast-flowing streams usually have clearer water and higher oxygen content than slow-flowing streams.

Rivers and Streams • Most nutrients that support life in flowing-

water ecosystems are washed into the water from land.


• In areas where the water movement slows, such as in the pools of streams or in large rivers, debris settles to the bottom.

• These environments tend to have higher nutrient levels and more plant growth.

Human Impact

• Once regarded as a free place to dump sewage and other pollutants, many people now recognize the damage this causes.


Lakes and Ponds• When a low place in the

land fills with rainwater, snowmelt, or water from an overflowing stream, a lake or pond might form.


• Pond or lake water hardly moves. It contains more plants than flowing-water environments contain.

Lakes and Ponds• Lakes are larger and deeper than ponds.


• They have more open water because mostplant growth is limited to shallow areas along the shoreline.

Lakes and Ponds

• Colder temperatures and lower light levels limit the types of organisms that can live in deep lake waters.


• Floating in the warm, sunlit waters near the surface of freshwater lakes and ponds are microscopic algae, plants, and other organisms known as plankton.

Lakes and Ponds• A pond is a small, shallow body of water.


• Because ponds are shallow, they are filled with animal and plant life.

• The warm, sunlit water promotes the growth of plants and algae.

• Because of the lush growth in pond environments, they tend to be high in nutrients.

Water Pollution

• Fertilizer-filled runoff from farms and lawns, as well as sewage dumped into the water, can lead to excessive growth of algae and plants in lakes and ponds.


• The growth and decay of these organisms reduces the oxygen level in the water, which makes it difficult for some organisms to survive.

Water Pollution

• People are being educated about problems associated with polluting lakes and ponds.


• Fines and penalties are issued to people caught polluting waterways.

Wetlands• Wetlands are regions that are wet for all or

most of a year.


• Other names for wetlands include swamps, bogs, and fens.

• They are found in regions that lie betweenlandmasses and water.

Wetlands

• They are fertile ecosystems, but only plants that are adapted to waterlogged soil survive there.


• Wetland animals include beavers, muskrats, alligators, and the endangered bog turtle.

Wetlands• Only recently have people begun to

understand the importance of wetlands.


• Products that come from wetlands, including fish, shellfish, cranberries, and plants, are valuable resources.

• Now many developers are restoring wetlands, and in most states access to land through wetlands is prohibited.

Saltwater Ecosystems• About 95 percent of the water on the surface

of Earth contains high concentrations of various salts.


• Saltwater ecosystems include oceans, seas, a few inland lakes such as the Great Salt Lake in Utah, coastal inlets, and estuaries.

Open Oceans

• Scientists divide the ocean into different life zones, based on the depth to which sunlight penetrates the water.


• The lighted zone of the ocean is the upper 200 m or so.

Open Oceans

• Below about 200 m is the dark zone of the ocean.


• Animals living in this region feed on material that floats down from the lighted zone, or they feed on each other.

Coral Reefs• Coral reefs are formed over long periods

of time from the calcium carbonate shells secreted by animals called corals.


• When corals die, their shells remain.

• Over time, the shell deposits form reefs.

Coral Reefs

• Reefs do not adapt well to long-term stress.


• Runoff from fields, sewage, and increased sedimentation from cleared land harm reef ecosystems.

Seashores

• The shallow waters along the world’s coastlines contain a variety of saltwater ecosystems, all of which are influenced by the tides and by the action of waves.


• The intertidal zone is the portion of the shoreline that is covered with water at high tide and exposed to the air during low tide.

Seashores33Aquatic EcosystemsAquatic Ecosystems

• Organisms that live in the intertidal zone must be adapted to dramatic changes in temperature, moisture, and salinity and must be able towithstand the force of wave action.

Estuaries

• The area where a river meets an ocean and contains a mixture of freshwater and salt water is called an estuary (ES chuh wer ee).


• Other names for estuaries include bays, lagoons, harbors, inlets, and sounds.

Estuaries

• Salinity in estuaries changes with the amount of freshwater brought in by rivers and streams, and with the amount of salt water pushed inland by the ocean tides.


• Estuaries are extremely fertile, productive environments because freshwater streams bring in tons of nutrients washed from inland soils.

Estuary Life

• Organisms found in estuaries include many species of algae, salt-tolerant grasses, shrimp, crabs, clams, oysters, snails, worms, and fish.


• Estuaries also serve as important nurseries for many species of ocean fish.

33Section CheckSection Check

Question 1

Which is NOT a type of wetland?

A. bayB. bogC. fenD. swamp

Question 2

Answer

Explain why ponds contain more vegetation than lakes contain.

Ponds are shallower than lakes. Because ponds are shallow, they are filled with animal and plant life. The warm, sunlit water promotes the growth of plants and algae. Fewer organisms live in the deeper water of lakes.



Question 3

The area where a river meets an ocean and contains a mixture of freshwater and salt water is called a(n) _______.

A. bogB. estuaryC. fenD. intertidal zone

The End

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Aquatic Ecosystems 6.L.2.3 Summarize how the abiotic factors (such as temperature, water, sunlight, and soil quality) of biomes (freshwater, marine, forest,